The objectives of this project are to assess the value of methods that can be used to disclose microbiological components in healthy and diseased gingival crevices (periodontal pockets). Phase contrast microscopy, appropriate cultural methods, and fluorescent antibody procedures are used to detect microorganisms that are present in high numbers and/or are of special interest. Changes in bacterial populations are followed during aggressive treatment of lesions; also fluctuations in the prevalence of motile forms are followed in patients on maintenance programs.